Model Output Discussion 12hrs. 01/10/13

[Cheshire Freeze]

That chart pretty much shows the only way to get snow in October, the Stoke city of synoptics, the northerly sourced straight from the north pole. Route one 

In the reliable, it looks an absolute mess, with cold pools, amplified patterns and even ex-tropical depressions all trying to get in on the act here. Some of these want to cut the high off to our north allow blocking to set up, others want to get the Azores high in. The plot thickens and expect models to throw a large variety of long term solutions beyond the initial northerly for the end of this week.

 

A very interesting and quite unusual set up for mid autumn. The snow looks to pile up across Siberia.

[Jonan92]

Well, it's rather improbable, but that setup shows a displaced vortex. If the ride of our side linked up with the one in the artic we will hace a big ride on that side and on the other side the vortex. However, it is too early to see something like that

 

Something similar to this

 

[kumquat]

The high is in - it isn't going anywhere much. There's a serious cold build into the NE. Like somebody said before (Steve M?) the shocker's coming end of October.

[Polar Maritime]

Way out i know, but just look at that for Greenland blocking...

 

Edited October 7, 2013 by Polar Maritime

[Frosty.]

Way out i know, but just look at that for Greenland blocking...

 

BANK     

[bluearmy]

low res gfs op strongly -AO ................. Thats just gfs low res - useless but fun to see. Hadst seen the 18z. Hmmmm. thats a repeating pattern i'd be happy to see!

[Tim Bland]

Wow there realy are some stunning northern hemisphere patterns showing. Some readers may not understand the excitement on here. It's not that is going to snow in the next few weeks, more the long term potential. At this time of year I would expect a flat pattern with low after low lining up in the Atlantic with our name on it. The PV is usually winding itself up over Greenland. If these blocking / negative NAO patterns continue, it's going to be a long winter!!

[Tamara]

Blocking to the north is very common in October and can mean very little for the winter on its own, and a cold blocked October like 1974 went on to provide an exceptionally mild zonal winter. Of much more value and interest will be the right feedback processes keeping in place like last autumn with the Asian snowcover and the stratospheric polar profiles being favourable. So far so good - but it is very early, especially in terms of gauging how the stratosphere is going to behave. A few more weeks progress needed yet.

 

In the short term the sort of pattern that would produce excitement in a couple of months is set to produce ordinarily chilly conditions and cold rain for many eastern and south eastern districts which is nothing to get enthusiastic about at all. At least north western districts look set for some fine weather, albeit not of the Indian Summer variety.

 

It seems that the upper trough is destined to hang around over the nearby continent through the whole of next weekend bringing the threat of further wet weather to southern areas - although there is often the propensity of the models to make rather a meal of these features and they tend to 'warm out' more readily than suggested

Edited October 7, 2013 by Tamara תָּמָר

[Summer Sun]

Latest from Gibby colder this week less chilly next week?

 

Good morning. Here is the report on the midnight outputs from GFS, UKMO, GEM, NAVGEM and ECM for today Monday October 7th 2013.

 

All models show a change in the weather this week as the mild SW flow covering the UK in the next few days switches to a much colder North or NE flow late in the week with High pressure than close to the North or NW. While the weather remains mild the rather cloudy SW flow will deliver some rain at times to the North sinking South tomorrow. Thereafter brighter and colder conditions from the North will introduce the risk of frost in the North overnight and some showers in strong winds to the East and SE at the end of the week.

 

GFS then continues the unsettled theme for the South while the North maintain largely dry and rather cool weather over the weekend. Through next week the unsettled weather in the South is shown to extend further North accentuated by new Low pressure feeding in from off the Atlantic to give all areas a changeable pattern with rain at times and temperatures recovering a little at least for a time.

 

UKMO this morning shows High pressure drifting NE over Northern scotland next weekend with an Easterly flow across the South which would be rather cloudy and cool with some occasional rain likely while the North would stay dry with some clear or sunny intervals especially in the NW where some overnight fog and patchy frost could occur.

 

GEM also shows an GFS type pattern with Low pressure near the South next weekend pushing it's influence further North as we enter the new week with rain at times and temperatures near average at best. The weather is then shown to become tranquil with light winds, a lot of misty low cloud with the chance of further mostly light rain and drizzle scattered about especially in the West and South.

 

NAVGEM shows a slack Easterly flow across Britain at the end of the weekend with a filling Low to the South still allowing some patchy rain or drizzle in the South in what looks like largely cloudy skies for most of the UK and temperatures close to average at best.

 

ECM too shows an unsettled weekend in the South as low pressure from Europe rests across Southern England at the start of next week. Cloud, showers or more persistent rain could affect the South, some of which could be heavy and thundery in temperatures held at normal values if not a little below. The North stays dry and potentially quite bright, especially towards the NW. The end of the run this morning shows High pressure making something of  a comeback ridging down from the North holding the Atlantic at bay with fine, settled and bright weather returning with fog an issue should this pattern evolve. 

 

The GFS Ensembles show a cooler snap before temperatures are shown to recover to nearer normal values in more changeable conditions than currently in the South with the North though having a dry period late in the week joining in with the more unsettled regime next week.

 

The Jet Stream shows the flow to the NW splitting in the week with a portion extending South over Britain midweek feeding the Low cell near SE England later in the week. The mainflow will then realign across the Atlantic absorbing the weaker circulation in the SE while a second arm lies way way North of the UK. The Southern arm is then shown undecided in its position next week.

 

In Summary the weather looks like changing firstly to a colder pattern from midweek with some showers in the East before this shower risk transfers to Southern areas by the weekend while the North close to High pressure to the North stays dry and rather chilly with some mist, fog and frost possible at night. Then through the second half of this morning's outputs most models show developments in the Atlantic could have an effect on conditions over the UK later with the risk of some rain or showers extending to all areas next week though still with some dry and benign weather around too. Also shown is a return to somewhat less chilly conditions as winds look like settling more from the South or SW.

 

http://www.norton-radstockweather.co.uk/Model-Analysis(2859336).htm

[snowmadchrisuk]

Wow there realy are some stunning northern hemisphere patterns showing. Some readers may not understand the excitement on here. It's not that is going to snow in the next few weeks, more the long term potential. At this time of year I would expect a flat pattern with low after low lining up in the Atlantic with our name on it. The PV is usually winding itself up over Greenland. If these blocking / negative NAO patterns continue, it's going to be a long winter!!

What worries me with this sort of pattern setting up now in October , is that when the real window for Cold is open , (Late Dec-Feb) We will have the blocking replaced by a raging P/V over Greenland. Greenland is not going to remain blocked for 5 months now is it ... I would say the signs this year are for a higher than usual chance for an early snow event , but Wet and Windy come new year ... Of course that is just a hunch, and it could be the best Winter ever.... As for current weather the forecast is for a cloudy day , but it is currently hot and sunny in Somerset at the moment and any fog at least in my area has already burnt away. A few Snow showers look possible in Eastern Scotland by the end of the week though.

[SMU]

Morning All-

 

I think what we see from the models this morning in terms of the longwave pattern out to 144 looks pretty reasonable to me-

 

Turning chilly with frost in the prone areas & general poor conditions for the E & NE zones.. these conditions then ease to the weekend...

 

Post that the models are now churning through the 'what happens next' scenarios, now for whatever reason ( which we don't know) the GFS will generally want to push the atlantic through the high, the Euros will better grip the pattern-

 

So the discussion point whether we get retrogression or a sinker will be in the mix for the next 72 hours-

 

What I would say is the building blocks for any retrogression will be at 120-144 in the form of the negative tilted low slipping north over Greenland-

 

My feelings is actually pretty clear on this one around-  we WILL see retrogression & some undercutting but wont see any real cold from the NE, that will be reserved for Scandi- with snowcover developing there.

The GFS will keep wanting to push the atlantic through- but finally work it out-

 

one to note is the UKMO 144 & the ECM show STRONG signs of retrogression being the form horse NOT the atlantic...

 

IGNORE the GFS ensembles they will be bin fodder.

 

 

That's the forecast ...... not the balanced model view..

 

S

[Methuselah]

My bin is already overflowing, Steve...It's got everything in it bar the pressure anomalies and upper wind indicators...

[Summer Sun]

Looking at the ECM Op and ensemble we are looking at 2 days of colder 850 uppers before a gradual rise from t120 (Saturday) at the same time the south east looks like seeing the rain whilst those further north would see the best of the sunshine

 

 

 

As per last night we could see a risk of frost and more especially fog developing from the weekend and into next week

Edited October 7, 2013 by Summer Sun

[shedhead]

Is anyone else currently struggling to get on wetterzentrale?

[SMU]

Im off to work now but maybe a challenge to keep things ticking on...

 

what crucial area of the UKMO 144 shows the high is going to retrogress-~?

 

 

http://www.meteociel.fr/ukmo/runs/2013100700/UN144-21.GIF?07-07

 

S

[No Balls Like Snow Balls]

No sign of anything remotely warm for the whole of the ensemble mean run on the ECM 00Z. Looks like slightly below to average.

Should be some very cold nights with all this HP around

[smithyweather]

Could somebody actually tell me what the PV would look like? And what is the MJO??

[shedhead]

Assume thats a no then!

[Captain Shortwave]

No sign of anything remotely warm for the whole of the ensemble mean run on the ECM 00Z. Looks like slightly below to average.

Should be some very cold nights with all this HP around

If the BBC is correct, only Thursday night will have a widespread frost with night time temperatures picking up again from Friday. Also cloud may become an issue by the weekend with milder air infiltrating the flow in the north. 

Also if the GFS/ECM were correct then there could be outbreaks of rain anywhere from Sunday onwards away from the far north of Scotland so it isn't even that settled an outlook.

Temperatures don't actually drop into single figures here, sums it up really.

Edited October 7, 2013 by Captain shortwave

[AWD]

Could somebody actually tell me what the PV would look like? And what is the MJO??

http://en.m.wikipedia.org/wiki/Polar_vortexhttp://en.m.wikipedia.org/wiki/Madden–Julian_oscillation Edited October 7, 2013 by AWD

[MP-R]

Assume thats a no then!

 

I too have had trouble with wetterzentrale but more with their archive charts for this year. I would also like to know what's up with it.

[Yarmy]

Could somebody actually tell me what the PV would look like? And what is the MJO??

 

Informally, a "bad" PV would look like a large deep purple/black blob over Greenland/Baffin Island extending over the pole. Positioned there it would give us mild zonal conditions over Winter. We look for it to be displaced or disrupted or split or just generally wiped out.

Edited October 7, 2013 by Yarmy

[Captain Shortwave]

Im off to work now but maybe a challenge to keep things ticking on...

 

what crucial area of the UKMO 144 shows the high is going to retrogress-~?

 

 

http://www.meteociel.fr/ukmo/runs/2013100700/UN144-21.GIF?07-07

 

S

It won't

Remember back to mid-September with Hurricane Humberto, you have a similar pattern killer here moving up the East coast of the states.

That low shown with the circle will phase with the Atlantic low and will move north east, this will force the Azores high North East and allow it to cling onto the high to our North. It's a sinker and that low is on both the UKMO/GFS and NAVGEM those the result on the latter still looks cold with the high sinking slower.

If you want retrogression, you want that low to disappear from the output pretty quickly.

[Jonan92]

Informally, a "bad" PV would look like a large deep purple/black blob over Greenland/Baffin Island extending over the pole. Positioned there it would give us mild zonal conditions over Winter. We look for it to be displaced or disrupted or split or just generally wiped out.

 

This

 

[Swave Snow]

It won't

Remember back to mid-September with Hurricane Humberto, you have a similar pattern killer here moving up the East coast of the states.

That low shown with the circle will phase with the Atlantic low and will move north east, this will force the Azores high North East and allow it to cling onto the high to our North. It's a sinker and that low is on both the UKMO/GFS and NAVGEM those the result on the latter still looks cold with the high sinking slower.

If you want retrogression, you want that low to disappear from the output pretty quickly.

 

 

Hi Captain,

 

I disagree,  I think the Jet is diving too far south to allow what you are suggesting to happen on this frame of the output from the UKMO.  Rather because of the buckled Jet, the High will be forced to retrogress NW towards Greenland and the Low to come into the mid atlantic.  I think I see where Steve M is coming from here..

 

Thats what I see from this 144 UKMO